1. Field of the Invention
The invention relates to valves, and particularly to four way ball valves, however certain aspects of the invention (e.g., an improved seat/seal assembly) can also be advantageously utilized in other types of valves.
2. Discussion of Background
FIG. 6 schematically depicts a conventional four way valve. The arrangement can accommodate two inlet flows and provide two outlet flows, and can be used where it is desired to switch or alternate the fluid flows to be fed to different parts of a fluid system. By way of example, a fluid flow system might utilize different fluids and, periodically, it is desired to switch or change the fluids which are to be fed into different flow paths of the system. As shown in FIG. 6, utilizing a four way valve, a single valve can switch a pair of inlets and outlets to change the relationships of the inlets and outlets. The valve of FIG. 6 includes inlets 1, 3 and outlets 2, 4, with the position of the ball closure 6 determining the communicating relationships of the inlets and outlets. In the position shown in FIG. 6, the inlet 1 communicates with the outlet 4 and the inlet 3 communicates with the outlet 2. By rotating the ball closure 6 by 90xc2x0, the inlet 3 then communicates with the outlet 4, and the inlet 1 communicates with the outlet 2. Thus, the inlet 1 can be selectively placed in communication with the outlet 2 or the outlet 4, while the inlet 3 is in communication with whichever outlet is not in communication with inlet 1.
FIG. 7 is an enlarged cross-sectional view of the ball closure 6 for the four way valve of FIG. 6. As shown, the closure 6 includes two bores 6a, 6b to provide two flow paths between the inlets 1, 3 and outlets 2, 4 as discussed above with reference to FIG. 6. One of the problems with such a prior art valve is that, in order to accommodate for the bores 6a, 6b, the size of the ball closure is large. In addition, due to the size of the ball closure, the torque required to rotate the ball is also large, and the actuator (the device which turns a valve) must therefore be sized to be able to overcome this torque.
The conventional four way valve is undesirable in a number of respects. First, due to the size of the ball closure, the other components of the valve, such as the housing, seats/seals, stems, linkages, must be larger, resulting in higher raw materials costs. In addition, higher manufacturing costs are encountered in forming the various components. The excessive size for a given bore size for the conventional four way valve not only results in excessive costs, but also, the size for which the valve can be practically manufactured is limited. For example, with the conventional arrangement, it is impractical to manufacture valves which are larger than 6xe2x80x3-8xe2x80x3 in bore diameter, since the overall valve size becomes excessively large.
As an alternative to the use of a four way valve, a series of valves and additional piping can be utilized. For example, as shown in FIG. 8 (in which inlet and outlet numbers corresponding to FIG. 6 are designated similarly, with the addition of ten), an inlet 11 can alternatingly feed outlets 12, 14 utilizing a pair of valves 16a, 16b. In particular, when the valve 16a is xe2x80x9con,xe2x80x9d and valves 16b and 16c are xe2x80x9coff,xe2x80x9d the flow passes from the inlet 11 to the outlet 12. When valves 16a and 16d are xe2x80x9coffxe2x80x9d and the valve 16b is xe2x80x9con,xe2x80x9d the flow passes from the inlet 11 to the outlet 14. Similarly, the flow from inlet 13 can be alternatingly fed to the outlets 12, 14, with the flow fed from 13 to 12 when 16c is xe2x80x9conxe2x80x9d and 16a and 16d are xe2x80x9coff,xe2x80x9d and with the flow from 13 to 14 when valves 16b and 16c are xe2x80x9coffxe2x80x9d and valve 16d is xe2x80x9con.xe2x80x9d As should be readily apparent, such is more complex and expensive in that four valves and additional piping are required. Moreover, the system is further complicated in requiring a control system which turns the valves on and off in concert.
A further difficulty with the conventional four way valve resides in providing a reliable and durable seating arrangement. The seat or seal is a part which contacts the ball closure so that there is no leakage (or at least minimal leakage) around the ball closure (and the flow passes only through the bores of the closure without bypassing the closure). Since the ball closure moves over the seat as it is being moved to different positions, the seat can wear (causing leakage between the seat and the ball closure), particularly if the valve application calls for the valve to be repeatedly switched (e.g., a million cycles per year). To minimize leakage, a seal can be held tightly against the ball closure, however, particularly with the large conventional four way valve, a large torque is then required to move the valve, making it more difficult to control position and rapidly change the position of the ball closure.
Accordingly, an improved four way valve is needed.
It is therefore an object of the invention to provide an improved four way valve which is relatively easy to manufacture and which is smaller than the conventional valve for a given bore size or valve flow capacity. In accordance with the present invention, a standard ball closure is utilized with a pair of intersecting bores extending through the ball closure. An elliptical separator is then provided within the ball closure so that the cross-bores form two isolated passageways (or flow paths) through the closure, and thereby provide a four way valve closure. With this arrangement, the size of the closure for a given bore diameter is greatly reduced. By way of example, with a prior art four way valve as shown in FIG. 7, the ratio of the ball diameter to the bore diameter is approximately 3 to 1. In other words, a valve with a 6 inch diameter bore requires a ball which is approximately 18 inch in diameter. By contrast, with the present invention, the ratio of the ball diameter to the bore diameter can be reduced to 2 to 1 or less. Thus, a valve with a 6 inch diameter bore can be achieved having a ball with a spherical diameter of approximately 12 inches or less. As a result, materials costs are reduced, not only for the ball closure, but also for the other components of the valve, such as the valve housing, seats, stems, etc. Further, the torque required to turn the valve is reduced, and it can therefore also be possible to utilize a smaller actuator or other means for turning the valve. The invention also provides an improved sealing/seating arrangement in which the seal or seat is spring loaded against the closure member. As a result, a reliable seal can be maintained over a large number of cycles as discussed in further detail herein.